We had this problem with my oldest daughter. At first I handled it entirely the wrong way, which prolonged it. We had just moved, had a new baby and I was stressed, so when she would pee (everything was tile,except a rug in her room-which seemed to be her favorite spot!)I would get upset and angry. Then we were both like out of control children! I found that when I remained extremely calm and showed her how to clean up and handed much of the responsibility of cleanup over to her (I would do some followup cleanup) including having her put the wet things in a bucket, having her put them in the washer, etc. that the behavior started to resolve itself. We also made her a simple book that showed her acceptable behavior for when she felt angry and another simple book about appropriate toileting behavior. if you need further advice on making these "therapeutic books" let me know. They seem to make a big difference in family problem solving. Love is patient.
mother of a 6.5 year old and a 4 year old (both completely toileting capable for many years now)